INTERIM CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (unaudited) - CAD shares in Millions, CAD in Millions	Total	Common shares/Share capital [Member]	Additional paid-in capital [Member]	Accumulated other comprehensive loss [Member]	Retained earnings [Member]
Beginning balance (shares) at Dec. 31, 2014		166.1
Beginning balance at Dec. 31, 2014	CAD 5,610	CAD 2,185	CAD 36	CAD (2,219)	CAD 5,608
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	320				320
Other comprehensive (loss) income	12			12
Dividends declared	(57)				(57)
Effect of stock-based compensation expense	6		6
CP Common Shares repurchased (shares)		(2.3)
CP Common Shares repurchased	(490)	CAD (29)			(461)
Shares issued under stock option plan (shares)		0.2
Shares issued under stock option plan	CAD 17	CAD 21	(4)
Ending balance (shares) at Mar. 31, 2015	164.0	164.0
Ending balance at Mar. 31, 2015	CAD 5,418	CAD 2,177	38	(2,207)	5,410
Beginning balance (shares) at Dec. 31, 2014		166.1
Beginning balance at Dec. 31, 2014	5,610	CAD 2,185	36	(2,219)	5,608
Ending balance (shares) at Dec. 31, 2015		153.0
Ending balance at Dec. 31, 2015	4,796	CAD 2,058	43	(1,477)	4,172
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	540				540
Other comprehensive (loss) income	(4)			(4)
Dividends declared	(54)				(54)
Effect of stock-based compensation expense	6		6
Shares issued under stock option plan	CAD 6	CAD 7	(1)
Ending balance (shares) at Mar. 31, 2016	153.0	153.0
Ending balance at Mar. 31, 2016	CAD 5,290	CAD 2,065	CAD 48	CAD (1,481)	CAD 4,658